A major garda presence will be in place tomorrow afternoon for a commemoration event to mark the second anniversary of the murder of Real IRA terror chief Alan Ryan.

Associates and pals of Ryan will be watched by members of the Special Detective Unit as well as uniformed gardai when they meet at Ryan's family home in Grange Abbey Drive, Donaghmede, at 3pm.

A garda at Ryan's grave, above, which was defaced with graffiti reading 'Rat Scum'

They are expected to then march to Ryan's grave in Balgriffin Cemetery where well-known Republican Francis Mackey is due to deliver an oration.

Sources say that tensions remain high in north Dublin after Ryan's local church was defaced with two messages which threatened his younger brother, Vinny. Meanwhile, blood-red graffiti reading "Alan Ryan rot in hell" was sprayed on a wall within the grounds.

The vandalism happened at the Holy Trinity Church in Donaghmede where Ryan's funeral took place followed by a paramiltary-style procession to the cemetery.

It is suspected that the gang who had Ryan murdered carried out the attack on the church. The same mob are suspected of attacking Ryan's grave last year ahead of the first anniversary of his death.

Red spray paint was used to vandalise the grave with the insult "Rat Scum" painted on the headstone. Family keepsakes and small memorials were also defaced.

The grave has not been targeted this week.

Mackey, who will give the main graveside speech tomorrow, is the chairperson of the 32 County Sovereignty Movement.

In April of last year, he spoke at a commemoration for Real IRA member Ronan McLoughlin who was shot dead by gardai as he tried to flee a botched raid on a Securicor van near Ashford, Co Wicklow, in 1998.

On that occasion, he said: "Like any revolutionary struggle the greatest dangers always come from within.

"There are those dangers which the enemy foster and those dangers we foster ourselves through ill-discipline and reckless recruitment.

"This struggle requires those who can contribute to its advancement. It does not need those who would use the struggle for their own ends.

"The entry bar must be set higher, recent events demand it."

Yesterday, some of Ryan's family members took to their Facebook accounts to pay tribute to him, including his brother Eoin who said: "Time goes by but every time I'm stuck in a moment of memory that I carry with me, cherished, inspired, remembered.